a) 40 = 2³.5
24 = 2³.3
ƯCLN(40; 24) = 2³ = 8
ƯC(40; 24) = Ư(8) = {1; 2 ; 4; 8}
b) 80 = 2⁴.5
144 = 2⁴.3²
ƯCLN(80; 144) = 2⁴ = 16
ƯC(80; 144) = Ư(16) = {1; 2; 4; 8; 16}
c) 9 = 3²
18 = 2.3²
72 = 2³.3²
ƯCLN(9; 18; 72) = 3² = 9
ƯC(9; 18; 72) = Ư(9) = {1; 3; 9}
d) 25 = 5²
55 = 5.11
75 = 3.5²
ƯCLN(25; 55; 75) = 5
ƯC(25; 55; 75) = Ư(5) = {1; 5}